Alloy irons and steels



March 31, 1953 sp z ALLOY IRONS AND STEELS Filed Oct. 21, 1949 2 SHEETS-SHEET l Fwd.

INVENTOR.

KARL SPW'Z' ATTORNEY.

March 31, 1953 spn- ALLOY IRONS AND STEELS 2 SHEETS-SHEET 2 Filed Oct. 21, 1949 ALLOY N 12.5

STNNLESS STEEL 0.15 CARBON STEEL INVENTOR. I KARL SPH'Z ATTORNEY.

Patented Mar. 31, 1953 ALLOY IRONS AND STEELS Karl Spitz, Cleveland, Ohio Application October 21, 1949, Serial No. 122,617

10 Claims.

This invention relates to alloy irons and steel-s, as indicated, and more specifically to austenitic alloy irons and steels having a high degree of resistance to chemical corrosion generally and to acid corrosion in particular, and having, additionally, improved physical properties.

I have experimented extensively with alloy compositions and am very familiar with the attributes and physical characteristics of the various high alloy and low alloy. steels which have hitherto been developed andwhich have received widespread use in the specific fields to which they are adapted. Such steels are exemplified by the Well known austenitic chromium-nickel stainless steels, particulary 18% chromium, 8% nickel stainless steel, and also by the high nickel-molybdenum Hastelloy group, as for example, Hastelloy B which contains about 65% nickel, 30% molybdenum and iron.

It is noteworthy that although strenuous efforts have been directed toward the development of corrosion resistant steels, little success has been achieved in developing alloy steels which have any sustained resistance to the action of acids, even under moderate conditions of temperature. Needless to say, such existing alloys are even less effective under high temperature conditions or when exposed to corrosive products of combustion such as prevail in the operation of jet engines and gas turbines.

The alloy irons and steels which I have invented are primarily noteworthy for their high degree of resistance to chemical corrosion which is a very potent and troublesome factor in the food processing and chemical industries, including the petroleum refining industry. They are likewise very resistant to high temperature corrosion such as occurs in the aforementioned jet engines and gas turbines.

Thus, it is a primary object of my invention to provide a new group of alloy irons and steels characterized by their outstanding ability to withstand chemical corrosion.

Another object of my invention is to provide alloy steels of the character described, which will have a significant resistance to the corrosive action of aqua regia, and thus will lie, insofar as corrosion resistance is concerned, intermediate platinum and the most effective alloys presently known, such as the I-Iastelloy group.

Still another object of my invention is to provide a group of corrosion-resistant alloy irons and steels having improved physical properties 2 such as high tensile strengths and yield points whereby to obtain improved strength to weight ratios.

A further object of my invention is to provide. corrosion-resistant alloy irons and steels having certain desirable and improved electricaland. characteristics, particularly when magnetic formed as wires or filaments.

Still another object of my invention is to pro-i vide corrosion-resistant alloys of the character described, which are adaptable to a large variety of uses in that their physical characteristics can be varied; certain of the alloys beingyfor ex-. ample, readily machinable and workable, and certain others, forexampla-being hard and wear-- resistant.

Other objects and advantages of my invention will be apparent during the course of the following description.

For a graphic understanding of the characteristics and properties of the alloy irons and steels which I have invented, reference may be had to the accompanying drawings forming part of this application, in which,

Fig. 1 is a photomicrograph showing the structure of my alloy No. 123 as etched with aqua regia.

Fig. 2 is a photomicrograph'of the same magnification as Fig. 1, showing the structure of stainless steel 18:8 as etched with aqua regia.

Fig. 3 is a photomicrograph of the same magnification as Fig. 1, showing the structure of Hastelloy- B as etched with aqua regia.

Fig. 4 is a photomicrograph showing the structure of my alloy No. 132 as etched with picric acid.

Fig. 5 is a photomicrograph showing the structure of my alloy No. 134 as etched with picric acid.

Fig. 6 is a photomicrograph showing the structure in cross-section of a weldlayer of my alloy No. 123 as bonded to stainless steel 18:8 and etched with aqua regia. I

Fig. 7 is a photomicrograph showing the struc ture in cross-section of a weldlayer of my alloy No. 134 as bonded to a high carbon (.'75%) steel and etched with picric acid.

The alloys of my invention contain at least iron, no more than 1.70% carbon and four major alloying constituents or elements, namely,

" chromium, nickel, copper and molybdenum, each further found that the desired characteristics toward which my invention is directed, are generally obtainable without having any of said major alloying elements present in an amount in excess of about 20.00%.

In Table I, below, I disclose the composition of eleven specific alloys coming within the broad range of my invention, the characteristic of these alloys being their excellent corrosion resist ance, although it will be understood that certain of said alloys may have said property in a greater or lesser degree than other of said alloys, as will more fully appear hereinafter. Each alloy, in addition to its corrosion resistance, is characterized by a particular physical, electrical, or chemical property which is considered desirable for adapting the alloy to a specific use or application, these characteristics resulting from changes in the proportions of the constituent elements, as will appear more fully hereinafter.

TABLE I Percentage composition cause corrosion, the oxidizing influences perhaps being neutralized or inhibited by the reducing influences.

As a practical matter, it is, of course, very desirable that the aggregate total of the major alloyin constituents be kept as low as possible, consistent with the degree of corrosion resistance which is the object of the invention, as the alloying elements are relatively expensive and therefore greatly influence the end cost of the alloy compositions. A compromise must also be effected between the desire for optimum corrosion resistance on the one hand, and the necessity of providing alloy compositions having other desired characteristics, such as workability, ductility and strength, on the other hand.

The alloy steels listed in Table I are to some extent representative of the various compromises which can be efiected in the compositions while AlloyNo. 01' Ni Cu. Mo Ti C Si P Mn Fe .00 5.45 12.30 8.00 0.10 0.00 0. 27 Remainder. .11 14.30 0.00 8.40 0. 33 0.02 0.11 Do. .00 18.20 7.70 10.20 0. 20 0.02 0.12 Do. .00 4.85 15.37 0.00 0. 72 0.02 0.00 Do. .00 1.55 10.00 1.20 0. 20 0.22 010 Do. .12 14.00 0.42 0. 00 0.42 0.02 0.10 Do. .04 14.00 0.00 13.00 0.30 0.02 0.12 D0. .31 14.72 3.01 2.03 0.05 0.01 0. 20 Do. .25 15.30 5.47 0.23 0.10 0.02 0. 24 Do. .50 12.10 1.17 5.10 0. 0.2 0.02 0. 20 no. .00 13.02 4.93 5.74 0.00 0.02 0.20 Do.

It will be noted that the carbon range of my 35 still maintaining the desired degree of corrosionalloy compositions is that which is usually found resistance. in ordinary steel, the carbon being preferably It is noteworthy that the chromium content less than 1% of the total composition. It is to of the listed alloys lies below 17% and in some be understood that my alloys can contain and instances lies below 10%, such as in alloys Nos. usually will contain such incidental ingredients 121, 123 and 134, whereas it has heretofore been as are customarily present in ordinary steels, accepted that no significant corrosion resistant such ingredients including, for example, silicon, characteristics could be obtained in austenitic phosphorus, manganese and sulfur in small chromium-nickel steels which did not contain in amount. Although in the foregoing Table I, I excess of 10% chromium, as evidenced by the have separately stated the. percentages of such chromium content of the well known stainless ingredients which are present in the listed alloys, steels 18:8, 25:12, etc. I wish it to be understood that whenever such in- Despite this restriction in the chromium congredients are not separately stated, I intend the tent, it is aparent from an inspection of Figs. 1, terms iron and substantially all iron to em 2 and 3 of the drawings, that alloy No. 123 which brace not only pure iron, but also iron containing 5 has a. chromium content of 9.11% and a comthe aforementioned incidental ingredients in bined Cr-Ni content of under 23.50%, resists the amounts up to the maximum amounts usually action of aqua regia much better than the 18:8 found in steel. stainless or Hastelloy B. e combination o chromium d nickel i I have found alloy No. 123 to have about the the all ys i fl n h ili y of he alloys to best corrosion-resistance of the listed alloys, folresist oxidizing Corrosion Such as results from lowed closely however by alloy No. 13 1 and alloy oxidizing atmospheres or oxidizing chemicals in- Na 121, eluding oxidizing acids. The combined alloy In Fig 6 di t o pari n is possible o p f chromium. nickel, Copper h y tween 18:8 stainless steel and a weldlayer of num shows resistance not only to ox dizing coralloy 123 as etched by immersion in aqua T051011, but also wrrqswn P as regia. It will be evident that the resistance of results from reducing chemicals, includlng rethe stainless steel is quite poor Whereas alloy ,22 fig b or characteristic of y alloys No. 123 shows little evidence of attack. It is is their primary feature and results as afore- 21 ;3 5:225:ggg fi g of alloy 123 mentioned in their improved resistance to com- 5 d 7 h bined oxidizing-reducing influences such as are an 5 0W ac of pmncacld efiected by aqua regia on alloy No. 134 and, as 1s evident from Fig. 7, It appears that to obtain optimum corrosion the high carbon steelis strongly attacked by the resistance, a certain balance in the proportions acld Whereas the Field has little efi'ect 0n the of the individual major alloying constituents Weldlayel of 3 N0. must be obtained irrespective of the combined AS Shown in even y alloy No. 132 t0ta1 or aggregate of the alloying constituents. which ranks as a low corrosion-resistant member This balance seems to effect a. corresponding 0f the group, has excellent resistance t0 the equilibrium in the electro-chemical forces'which picric etch. The alloy h s n Subjected. h

5. out failure, to the standard Strauss corrosion test which is used for testing stainless steels.

- All of the listed alloys are austenitic, have high tensile strengths and yield points, and can be cast.

Table II below shows the results of tests I have conducted on various of the alloys with regard to tensile strength and reduction of area, in the cast condition.

TABLE II Tensile Strength Alloy No. ig fi concernm MEN- oomoaaaoomoocno Generally speaking, the high strength alloys, such as Nos. 121 and 125 have a relatively high molybdenum-copper content, whereas the more ductile alloys such as Nos. 162 and 208 have a relatively greater chromium-nickel content.

Since copper has a hardening effect on the alloys, which is aided by increases in the carbon, silicon and phosphorus content, alloys Nos. 125 and 129, especially when modified by an increased carbon content, are usable mainly as cast for wear-resistant and heat-resistant purposes. Their high copper content also increases their electrical conductivity and makes them suitable for use in the electrical industry.

Generally speaking, those alloys in which carbon does not exceed 0.3%, silicon does not exceed 0.5%, phosphorus does not exceed 0.05%, and manganese does not exceed 1.0%, are most suitable for wrought applications.

On the other hand, those alloys in which carbon is up to 1.7%, or silicon is up to 1.2%, or phosphorus is up to 0.5%, or manganese is up to 1.5%, are mainly suitable for cast applications.

As the chromium and nickel content influence the ductility of the alloys, as heretofore stated, all of the listed alloys, with the exception of Nos. 125 and 129, can be wrought, including forging and coldworking.

It is to be emphasized that all of my alloys are austenitic even after coldworking and that no intergranular corrosion occurs in the higher carbon alloys such as occurs in stainless steels when the carbon content exceeds about 0.10%.

In addition to alloys Nos. 125 and 129, alloy No. 121, due to its high copper content, is also suitable for electrical applications in the cast and forged condition.

Other of the alloys are capable of being drawn into fine wire which is austenitic and non-magnetic and therefore has applications in the electrical field, especially in the field of electronics. Alloys Nos. 132 and 200 are particularly suitable for this purpose.

I have successfully drawn alloy No. 132 into a fine wire of .004 diameter which had a tensile strength of about 300,000 p. s. i. and had a 15% greater electrical conductivity than like wire formed of 18:8 stainless steel. As heretofore stated, the wire is entirely austenitic and nonmagnetic.

The fact that, in general, a high degree of corrosion-resistance denotes acorrespondingly high degree of heat resistance, is evidenced by the fact that annealed wire formed of alloy No. 132 has about 30% greater tensile strength than like wire similarly treated and formed of 18:8 stainless steel.

The influence of changes in the total amount of major alloying elements present in a particular alloy composition, is indicated by tests I have conducted using alloy No. 132 as a basis.

Alloy No. 132, which contains a total of 38.14% of the major alloying elements, was tested for hardness and gave a Rockwell B reading of 72.

By increasing each major alloying element of alloy No. 132 proportionately to a total alloy content of l2.25%, alloy No. 200 was obtained which has a Rockwell B hardness of 8'7 and increased tensile strength.

By porportionately decreasing the total alloy content of alloy No. 132 to 32.23%, alloy No. 201

was obtained which showed a hardness of '70 Rockwell B and corresponding lower tensile strength.

All of my alloys are work hardenable and when so treated reach hardness values of about Rockwell C 32.

All of my alloys can be welded or brazed by conventional methods.

All of the alloys, but particularly alloys Nos. 123, 123a, and 134, are suitable for use as filler metal in welding.

-The alloys have demonstrated excellent creep resistance properties as well as a high degree of toughness as evidenced by notched-bar impact tests.

The foregoing description of the properties of my alloys indicates that they have numerous applications wherever corrosion resistance, high strength, and non-magnetic qualities are factors, especially where a combination of these properties is required.

In addition to the uses heretofore mentioned, my alloys may be used for such diverse purposes as springs, non-absorbable metallic sutures for surgery, marine equipment and devices, including roller bearings, architectural ornamentation, and components of valves, pumps and the like.

I have also found that my alloys have good tonal qualities which would permit of their use as bells, particularly in marine service.

The alloys are non-sparking and therefore are usable for tools utilized in mining operations and the like.

The alloys are also suitable for cladding applications and also appear to have application in low temperature fields of use.

It is to be understood that the particular alloy compositions herein listed are exemplary and illustrative of desirable alloy compositions, and that slight changes may be made in the proportions of the alloys without departing from the spirit of the invention as defined in the subjoined claims.

Having thus described my invention, II claim:

1. A ferrous alloy composed of more than 6.0% but not more than 20 each of chromium, nickel, copper and molybdenum, the sum total of said elements being less than 50 and the remainder being substantially all iron.

2. A corrosion-resistant ferrous alloy of the following composition: chromium about 9.11%, nickel about 14.30%, copper about 6.0%, molybdenum about 8.40%, and the remainder substantially all iron.

3. A corrosion-resistant ferrous alloy of the following-composition: chromium about 5.64%,- nickel about 14.0%, copper about 6.0%, molybdenum about 13.8% and the remainder substantially-all ;iron.

4A lcorrosioneresi'stant ferrous alloy of the following composition: chromium about 10.86%, nickel-.about4.85'%, copper-about 15.37%, molybdenum about 6%, and the remainder substantially all iron.

5. A corrosion-resistant ferrous :alloy of the following composition: chromium about 15.25%, nickel about. 15.30%, copper about 5.47%, molybdenum about 6.23%, and the remainder substantially call. iron.

6. A 'QOIIOSiOIkZBSiStfiHfi .ferrous alloy of the iollowmg composition: chromium about 12.60%, nickel-about 18.20 copper about 7.70 %,,1molybdenum about 10.80%, and the remainder substantially all iron.

7. A ferrous alloy composed of chromium, nickel, copper and molybdenum, each of said elements being present in an amount greater than 6% and less than 32% of the composition, the sum total of said elements being less than 50% of the composition, and the remainder being substantially all iron.

8. A steel alloy composed of chromium, nickel, copper and molybdenum, each of said elements being present in an amount greater than 6% and less than 32% of the composition, the sum total of said elements being less than 50% of the composition, carbon from about 0.01% to 10. A corrosion-resistant alloy steel contain ing at least 3.6% chromium, at least 3.6% nickel, at least 5.3% copper, at least 6% molybdenum,

the sum total of said-elements beingless than" of the composition, and the remainder looing substantially all iron.

KARL SPI'IZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,200,208 Parsons May 7, 1940 2,251,163 Payson July 29, 1941 2,402,814 Hatfield June 25, 1946 FOREIGN PATENTS Number Country Date 195,118 Switzerland Apr. 1, I938 

1. A FERROUS ALLOY COMPOSED OF MORE THAN 6.0% BUT NOT MORE THAN 20% EACH OF CHROMIUM, NICKEL, COPPER AND MOLYBDENUM, THE SUM TOTAL OF SAID ELEMENTS BEING LESS THAN 50%, AND THE REMAINDER BEING SUBSTANTIALLY ALL IRON. 